Fuel Filter Location

Coarse filter (about 100 micron) before the pump (to keep the big chunks out of the pump without putting too much restriction on the suction side), and a finer filter (about 40 micron) after the pump to protect the carb.

The factory did this with a "sock" filter in the tank and an inline filter after the pump. If you already have a sock filter in the tank, then you don't want or need another filter before the pump.